From Dr. Roy Spencer's Global Warming Blog
Author: Dr. Roy W. Spencer
generalize
- Previous research has shown that temperatures recorded in Death Valley National Park (DVNP) exhibit strange warm biases on very hot days, possibly due to instrumentation flaws or the proximity of installed structural equipment and other man-made structures.
- Here, based on data from the summer of 2021 (June, July, and August), it is shown that there are many more days when DVNP is much warmer than nearby Stovepipe Wells station than when Stovepipe Wells station is hotter than DVNP station.
- This evidence suggests that hot summer daytime temperatures reported in Death Valley National Park may be significantly biased and should only be used for recreational value.
In our ongoing examination of the world's highest temperature record of 134 degrees. F Recorded on July 10, 1913 at Greenland Ranch (now Death Valley National Park Station), where we noticed some strange behavior in recent summer temperatures. (Bulletin of the American Meteorological Society [BAMS] My proposal for the BAMS article showing evidence of 134 degrees has been accepted. The F world record is 8 to 10 degrees. F is higher than the value that actually existed on that date [10 July 1913]).
Previous research on excessive temperatures in Death Valley
Weather forecaster and storm tracker Bill Reid has blogged over the years about the evidence against 134-degree temperatures. F world record. A good place to start is his recent post (Part 6) about a Greenland ranch foreman who took excessively high temperature measurements in the first half of July 1913. I.
During 2021 and 2022, an experiment was also conducted on various temperature instruments placed next to the DVNP weather station. Official” DVNP sensors produce temperatures several degrees higher than other instruments (AMS conference poster here). The photo in Figure 1 shows an older DVNP instrument (non-breathing) installed next to a large metal structure and small solar panels.
Figure 1 Death Valley National Park weather station with additional instruments added by Dirk Baker (Campbell Scientific, Inc.) and cooperating researchers to compare with “official” temperature readings in 2021 and 2022. Adapted from this AMS conference presentation) ).
The experimental setup in Figure 1 uses multiple temperature sensors, some with air-breathing shields and some without air-breathing shields. The data shown in their AMS conference presentation indicated to me that it was close to the recorded 130 degrees. The F reading on July 9, 2021 was 2-3 degrees. Part of the reason F is too hot is the non-breathing design of the sensor. There is some additional warm bias, which may be caused by all the mounting structures shown in Figure 1, including the small solar panels next to the DVNP station sensors.
More Evidence: DVNP and Chimney Well Temperature
Over the past 21 years, two monitoring stations have been established in Death Valley: the DVNP Monitoring Station located next to the Furnace Creek Visitor Center and the Climate Reference Network (CRN) Monitoring Station at Stovepipe Wells, 29 kilometers northwest of the DVNP Monitoring Station.
Figure 2 shows a comparison of the daily maximum temperatures (Tmax) recorded at these two sites in June, July and August for the calendar years 2004 to 2024.
Figure 2. Comparison between daily high temperatures (Tmax) recorded at Chimney Wells and Death Valley National Park for all days in June, July, and August from 2004 to 2024. Difference station (2°F, DVNP warmer than Stovepipe Wells). Gray lines connect days in chronological order.
The median difference in Tmax between the two sites was 2 degrees. F (DVNP warming, represented by the red dashed line), while the average difference is 2.3 degrees. F. The expected difference based on altitude alone is 1.3 degrees. F (DVNP station elevation is 278 feet lower than Stovepipe Wells).
Note that in Figure 2, there appear to be more outliers to the left of the red dashed line than to the right. That is, the number of days on which DVNP is much warmer than the Stovepipe Wells station is greater than the number of days on which the Stovepipe Wells station is much warmer than the DVNP station.
This can be seen better if we look at the frequency distribution of these site differences (adjusted to 2 degrees). F Median differences between sites (Fig. 3).
Figure 3. Frequency distribution of days when one site in Death Valley is hotter than another. This is the result after shifting the distribution by 2 degrees. F difference median difference.
As shown in Figure 3, the number of days that DVNP station is hotter than Stovepipe Wells is greater than the number of days that Stovepipe Wells is hotter than DVNP station. For 3-4 degrees. F Hotter category, the difference is 2 times, 5 to 9 degrees. F The difference in the hotter category is 3 times, for 10 degrees. The difference for F or greater is 7.8X.
This suggests that there is a problem with the Death Valley National Park instrument itself or the immediate environment around the temperature sensor, causing some days to be too warm. Bill Reid, who has researched this issue extensively, suspects that on low-wind days, excessive heat builds up at the DVNP thermometer location, either in the general area around the instrument or due to the unusual nature of the temperature sensor used. Breathing design there.
The difference in exposure between the DVNP station and the Stovepipe well is shown in Figure 4.
Figure 4. Google Earth images of Stovepipe Wells Station (top) and Death Valley NP Station (bottom), stations circled in red. The top inset is a photo of the Stovepipe Wells Climate Reference Network Station, courtesy of William T. Reid. The east-west distance of these images is just over 0.5 km.
As shown in Figure 4, there is considerable development surrounding Death Valley National Park Station, with parking, paved campgrounds, visitor center, solar panels (black), and trees to the south. The Chimney Well site has little development and no vegetation. When southerly winds prevail in the summer, buildings and trees south of the DVNP station may cause stagnant airflow around the temperature sensor.
in conclusion
The evidence presented here, and previously presented by Bill Reed, Dirk Baker, and others, suggests that temperatures in Death Valley National Park should not be relied upon for accurate daytime readings, and that near-record temperatures there are on the higher side. The cause of the deviation is not obvious, but there is evidence that poor ventilation of the sensor during the day will heat up various nearby structures: whether it is the shielding of the sensor itself, its supporting structure or various structures around the site. Man-made objects. Trees and other structures south of the space station may also restrict air flow, further reducing effective convective heat transfer away from the solar-heated desert surface.
I think the “official” Death Valley temperatures should use Chimney Well field data from the state-of-the-art Climate Reference Network instruments. The traditional grounds adjacent to the Death Valley National Park Visitor Center may be used for recreational purposes only.
Perhaps the National Park Service should look into adding a CRN station; a good location would be about 1.6 kilometers southwest of the current station, away from the Furnace Creek tourist area.
Relevant
